Knee wraps done tightly enough can definitely offer some assistance in a heavy lift. The added stability makes it easier to squat weight. Some bodybuilders will put them on only a minute or two before their heavy lifts because the wraps are so tight they can limit circulation. However, they do offer some support that can be beneficial for people who have suffered an injury or have chronic knee pain. Therefore, it is okay to use them when doing heavy squats. Just do not start using them until you are moving serious weight.